Table 1. Thermodynamic parameters in the interaction between XIAP's BIR3 with Smac and caspase 9 linker peptides as measured by ITC.

N is the stoichiometry of the interaction (that is, the ligand/protein ratio).

Peptide sequence	10−6×Ka (M)	KD (μM)	ΔG (kcal/mol)	ΔH (kcal/mol)	N	−TΔS (kcal/mol)	[Ligand] (mM)	[Protein] (μM)
AVPIAQK (Smac)	3.099	0.308	−8.648	−6.768	1.025	1.88	2	110
SPGSNPE	0.00723	≫138	−2.258	−0.6579	1.671	1.6	10	110
ATPFQEG	3.24	0.322	−8.234	−7.059	1.175	3.78	2	110
AISSLPT	0.01156	80	−3.774	−1.421	2.353	4.155	6	110